A block of mass 10   kg , moving in x direction with a constant speed of 10   m  s - 1 , is subjected to a retarding force F = ( 0 .1 ) x   J   m - 1 during its travel from x = 20   m to 30   m . Its final kinetic energy will be:

Step-by-step solution

m = 10   k g ,   u = 10   m   s - 1 Final KE will be given by K E f = K E i + W = 1 2 m u 2 + ∫ 20 30 - 0 .1 x d x = 1 2 × 10 × 100 + - 0.1 x 2 2 20 30   = 500 + - 0.1 2 900 - 400 K E f = 500 + - 0.1 500 2 = 475   J